It is known to provide a slider window assembly for a rear opening of a pickup truck. Conventional slider window assemblies for rear openings of trucks or the like typically include three or more panels, such as two fixed window panels and a slidable window panel. The slidable window panel is supported by rails and may be moved along the rails to open and close the window. It is known to provide a heating element at the window assembly to defog or defrost the window panels. The fixed window panels typically include respective heater grids that are electrically connected to a power source and are heated responsive to actuation of a user input. The movable window panel typically includes a heater grid that is electrically connected the power source when the movable window panel is closed, whereby electrical terminals at the movable window panel may be electrically connected to or in electrical contact with electrical terminals at the frame or latch, and whereby the movable window panel is not electrically connected to the power source when the movable window panel is opened or partially opened.